Die casting



R. C. CORNELL Feb. 6, 1962 DIE CASTING 2 Sheets-Sheet 1 Filed May 28, 1958 INVENTOR ATTORNEY Feb. 6, 1962 R. c. CORNELL 3,019,495

DIE CASTING Filed May 28, 1958 2 Sheets-Sheet 2 INVENTOR ATTORNEY 3,819,495 DEE CASTING Robert C. QOI'EZBH, .laclrson, Mich, assignor to Liternetal Dicast, line, Jackson, Mich a corporation of Michi an g Filed May 28, 31358, Ser. No. 738,456

12 @iaims. (Qt. 22-68} The present invention relates to improvements in method and apparatus in the field of die casting machines.

It has heretofore been proposed in pressure die casting machines to cause a vacuum in the die cavity simultaneously with the injection of molten metal therein to re duce porosity. Reference may be had, for example, to the disclosure or" United States Patent No. 2,616,372.

According to the present invention, it has been proposed to remove the air from the cold chamber as well as from the die cavity prior to transfer of the molten metal from the cold chamber into the die cavity. In each of the several forms of the invention illustrated, the chamber between the sprue hole and the end of the injection plunger is preferably evacuated by withdrawing the air therefrom in a direction counter to the path of movement of the molten metal transferred by the plunger moving from the cold chamber to the die cavity. Also, in the illustrated forms of the invention it is preferred that the initim ejection movement of the plunger within the cold chamber will interrupt the withdrawal of air therefrom in the direction counter to the ejection movement of the plunger.

One form of the invention contemplates hand ladling of the molten metal into the pouring slot in the cold chamber, plugging the pouring slot and the evacuating air from the cold chamber through the pouring slot. Another form contemplates the use of a vacuum box connected to the pouring slot within which a ladle is housed and actuated. In a still further form of the invention the transfer of molten metal to the cold chamber is effected by evacuation of the cold chamber and controlled by a stopper in the source of molten metal.

Thus, an object of the invention is to provide an improved method of pressure die casting in which evacuation takes place in the cold chamber.

Another object of the invention is to provide an improved method of pressure die casting in which evacu ation takes place in both the die cavity and in the cold chamber.

Another object is to provide an improved method of pressure die casting in which the evacuation of the die is supplemented by evacuation of the cold chamber in a direction counter to the ejection of the molten metal from the cold chamber.

A further object of the invention is to provide a method of pressure die casting in which at least a portion of the evacuation of air takes place through the pouring slot associated with the cold chamber.

A still further object is to provide an improved method of pressure die casting in which the molten metal is supported within a vacuum box connected to the pouring slot of the cold chamber and is then transferred to the cold chamber following simultaneous evacuation of the box and the cold chamber.

A still further object of the invention is to provide practical structure of difierent forms herein illustrated for 3 ,h l 9,495 Patented Feb. 6, 1962 carrying out the stated objects of the preceding paragraphs.

These and other objects and advantages residing in the method and apparatus with which the present invention is concerned will more fully appear from the following specification and the appended claims.

In the drawings,

FIG. 1 is a diagrammatic showing of the invention applied to a conventional cold chamber pressure die casting machine,

FIG. 2 is a view similar to FIG. 1 of an enlarged portion of the showing of FIG. 1,

FIG. 3 is a slight modification of the structure employed in the evacuation of the cold chamber through pouring slot as compared with the showing in FIG. 1,

FIG. 4 is a view similar to FIG. 1, of a cold chamber type of pressure die casting machine in which a vacuum box housing the ladle is connected to the pouring slot,

FIG. 5 is a detail View of one of the elements shown in FIG. 4, and

FIG. 6 is a view similar to FIG. 4 of the principles of the invention applied to a cold chamber type of pressure die casting machine employing vacuum delivery of the molten metal to the cold chamber.

Referring to the drawings, in the diagrammatic showing of FIGS. 1 and 2 the cold chamber type of pressure die casting machine comprises a die generally consisting of an ejector portion 19 and a cover portion 12. A suitable vacuum box 14 is shown embracing the parting line of the die when closed. As shown, the box 14 comprises two parts 16 and 18 mounted on the die portions lit and 1 2, respectively, and abutting each other to complete the box, there being a suitable seal 20 carried by one of said parts 16 and 18. Between the portions it) and i2 is provided one or more radial passages 22 for the evacuation of the die cavity 24. An ejector plate 26 carries ejector pins 28, the lower of which in FIG. 2 is shown broken away to illustrate the hole Sil in the portion lit in which the associated pin 28 is reciprocated to eject the casting from the cavity 24 in a well known marnier.

The vacuum line 32 is shown with one of its connections to the vacuum box 14 and another or" its connections to the cavity 34 in which the ejector plate 26 is carried and operated by pins 36 located in the wall 38. In this manner, the cavity 24 may be quickly and ellectively evacuated with the elimination of leakage of air from the ambient atmosphere through the parting line or through clearances surrounding the ejector structure. The line 32- extends to a suitable source of vacuum with a. suitable valve 40 being inserted to vent the box 14 and cavity 34 to the atmosphere as may be required by the sequence of operation of the die casting machine. This structure just described has been found capable of practical and effective evacuation of the die cavity 24, sprue hole gate and runner structure defined between the die portions lit and 12.

To complete the evacuation of the chamber or spacedefining structure connected with or leading to the parting line between the die portions 10 and 12, means are provided for evacuation of the cold chamber 42, preferably in a direction counter to the direction of movement of the plunger 44- upon transfer of molten metal from the chamber 42 to the die cavity 24. As illustrated in FIGS. 1 and 2, a pouring slot 43 is provided which opens into the chamber 42. A plug 46 is raised and lowered relative to the slot 43 by means of the lever 43 which, as shown, is actuated by a suitable cylinder 5i operated in proper sequence with the remaining parts or" the machine. The vacuum line 32 connects with the chamber 42 and slot 43 through the trap 52 and vacuum line 54. With the die portions and 12 closed and the plunger 44 moved to the right from its position shown in FIG. 1 to a position to the right of the slot 43, molten metal may be then ladled into the chamber 42 for transfer therefrom to the cavity 24. The plug 46 is then lowered into position to seal the slot 43 from the atmosphere. The valves it? are then actuated from venting to vacuum positions. Following the evacuation that thereafter takes place within the die casting machine from both ends of the total structure along which the molten metal traverses, the plunger 44 moves toward the position shown in FIG. 1 transferring the molten metal into the dies in the usual manner with such transfer taking place in the absence of any appreciable quantity of trapped air with the result that a die casting is produced having minimum porosity. Upon completion of each slot, the valves are moved into venting position and the casting and sprue associated with the cavity 24 is removed upon opening of the die portions 10 and 12 and the plunger 44 is returned to a position at the right of slot 43, as viewed in FIG. 1.

In FIG. 3, a slight relocation of the vacuum connection 54' is shown in association with the plug 46 rather than being disposed or defined within the wall defining the pouring slot 43' in the manner shown in FIG. 1.

FIG. 4 illustrates evacuation counter to the direction of molten metal transfer with the supply of molten metal being located Within an evacuated chamber 56 having a cover 58 actuated by some suitable means such as a cylinder 60. The vacuum connection 54" evacuates the chamber 56 as well as the cold chamber 42"; the connection between the chamber 56 and the chamber 42 being through the pouring slot 43". The molten metal supply is shown supported by the ladle 62 which is, in turn, supported for rocking movement within the chamber 56 and actuated by the external handle 64 to deliver molten metal through the slot 43" into the chamber 42". A suitable electric heater coil 66 is shown associated with the ladle 62. With the ladle 62 manually charged with a quantity of molten metal, the cover 58 is closed to seal the chambers 56 and 42" to the ambient temperature. Following, or during, evacuation the ladle 62 is tilted and the chamber 42" is charged with molten metal and the shot is made.

In FIG. 6 the molten metal from the pot 68 is raised by the evacuation of the cold chamber 42' through the vacuum line 52. The structure connecting the pot 68 through the chamber 42 takes the form of a member 70 having inlet opening 72 controlled by the plug '74 actuated by some suitable means such as the cylinder 76. A riser 78 connects with the chamber 42 through an opening 80 in the wall thereof. In operation, the evacuation of the chamber 42 takes place with the plug 74 in a closed position. Thereafter the plug 74 is raised to permit the desired charging with molten metal of the cold chamber 42" and, thereafter, the plug 74 is lowered into its closed position and the shot is made.

It will be understood that the die of the die casting machine is preferably being evacuated in the manner of FIG. 1 simultaneously with the evacuation of the cold chamber in the modification disclosed in FIGS. 4 and 6.

Having thus described my invention what I claim is new and desire to protect by Letters Patent is:

1. A method of pressure diecasting of molten metal in a cold chamber type of machine in which the molten metal is first delivered to the cold chamber through an opening in the cold chamber and then mechanically transferred therefrom to the die under pressure comprising the step, following the delivery of molten metal into the cold chamber, of evacuation of the cold chamber in a direction counter to the direction of mechanical transfer of the molten metal into the die and through the opening through which the molten metal is delivered into the cold chamber.

2. A method of pressure diecasting of molten metal in a cold chamber type of machine in which the molten metal is first delivered to the cold chamber through an opening in the cold chamber and then mechanically transferred therefrom to the die under pressure comprising evacuation of the cold chamber in a direction counter to the direction of mechanical transfer of the molten metal into the die and through the opening through which the molten metal is delivered into the cold chamber and employing the initial movement of the transfer structure to interrupt the evacuation path with the cold chamber.

3. A method of pressure die casting in a cold chamber type of machine having a pouring slot in the cold chamber, the steps of evacuating a space connected to the pouring slot, supporting a supply of molten metal in said space while said space is being evacuated simultaneously with the evacuation of said cold chamber and then transferring the supply of molten metal from said evacuated space into said cold chamber just prior to the interruption of communication between said cold chamber and said space by the mechanical transfer of the molten metal from said cold chamber into the die.

4. A method as defined in claim 3 wherein the transfer of the supply of molten metal from said space into said cold chamber is by gravity.

5. A method of pressure diecasting molten metal in a cold chamber machine in which the molten metal is first delivered to the cold chamber through an opening in the cold chamber and then mechanically transferred therefrom to the die under pressure, comprising the steps of pouring the metal into the cold chamber through the opening in the cold chamber and then evacuating the cold chamber in a direction counter to the direction of mechanical transfer of the molten metal into the die and through the opening through which the molten metal is delivered into the cold chamber.

6. A method of pressure diecasting molten metal in a cold chamber machine in which the molten metal is first delivered to the cold chamber through an opening in the cold chamber and then mechanically transferred therefrom to the die under pressure, comprising the steps of pouring the metal into the cold chamber through the opening in the cold chamber and then evacuating the cold chamber in a direction counter to the direction of mechanical transfer of the molten metal into the die.

7. A machine for the pressure die casting of molten metal of the cold chamber type in which molten metal is first delivered to said cold chamber and then mechanically transferred to the die under pressure comprising a die, a cold chamber, means in said chamber to transfer molten metal from said chamber to said die, a pouring slot in said chamber, a vacuum box connected to said slot, a container for molten metal supported in said box, means for the evacuation of said box and chamber, and means for the delivery of molten metal from said container to said cold chamber through said slot.

8. A machine as defined in claim 7 wherein said container is in the form of a rockable ladle.

9. A machine as defined in claim 7 wherein said container has heating means associated therewith.

10. A machine for the pressure die casting of molten metal of the cold chamber type in which molten metal is first delivered to said cold chamber and then mechanically transferred to the die under pressure comprising a die, a cold chamber, means movable in said chamber to transfer molten metal from said chamber to said die, an opening defined in said chamber for the delivery of molten metal to said chamber means defining a passage communicating with said opening, means for closing said References Cited in the file of this patent opening to the ambient atmosphere, and means for evac- UNITED STATES PATENTS uating said chamber and said passage between said chamber and opening closing means. 1,112,694 Grey 1914 11. A machine as defined in claim 10 wherein said 5 2112343 Lester 1938 means for closing said opening is in the form of a box, 2243835 Brunner June 1941 means in said box for supporting a supply of molten 2799066 Federman at July 1957 metal, and means for delivering molten metal from said FOREIGN PATENTS supply to said chamber through said opening.

12. A machine as defined in claim 10 wherein said 10 means for closing said opening is in the form of a plug.

615,484 Great Britain Jan. 6, 1949 313,426 Switzerland May 31, 1956 

